Volvo loader L90-L120 steering valve , Iran

SAUER DANFOSS volvo loader steering unit

The steering orbital valve supplied by Sauer‑Danfoss for Volvo loaders is engineered for high precision and long service life. The metering unit is machined to tolerances below 10 microns, ensuring repeatable steering response with minimal hysteresis. Hydraulic service pressure is typically rated 210 bar with peak resistance up to 250 bar, and internal leakage is minimized to achieve volumetric efficiency above 90 percent. Components like the rotor, stator and control slide are made from high strength alloy steels with surface hardening to Rockwell C 55–60, enhancing wear resistance under abrasive fluid conditions. Quality control includes 100 percent pressure testing and flow calibration to maintain consistent performance across production batches.

In operation, the Sauer-Danfoss steering unit supports flow rates from 30 up to 65 liters per minute depending on loader size, ensuring smooth, proportional steering even at low engine speeds. The valve body and spool surfaces are finished to Ra 0.4 or better, reducing turbulence and cavitation. Hydraulic ports are compatible with standard metric or SAE fittings, and seals are selected for high temperature stability from -30 to +120 degrees Celsius. This robust design yields long mean time between failures and predictable control feel under variable load cycles.

Factors that cause defect in volvo loader steering unit

Failure of the steering rack in Volvo loaders L90, L120, and L180 typically begins with gear tooth wear and increased axial backlash. Hydraulic pressure dropping below 160 bar reduces steering assist force significantly. Pump flow decreasing under 30 liters per minute leads to delayed steering response. Oil contamination with particles larger than 10 microns accelerates surface scoring and friction. Backlash exceeding 0.3 millimeters causes impact loads during directional changes. Hydraulic oil temperature above 90 degrees Celsius accelerates seal degradation and internal leakage.

Common symptoms include steering free play exceeding 5 degrees at the steering wheel. Knocking noise during turns greater than 30 degrees indicates advanced gear wear. Steering response delay longer than 0.5 seconds suggests internal leakage or flow restriction. Visible hydraulic oil leakage around cylinders or fittings is a critical warning sign. Pressure spikes above 250 bar during static testing may indicate return line blockage. Proper filtration and periodic pressure and flow testing can extend steering rack service life by at least 20 percent.